Charge-neutral fermions and magnetic field-driven instability in insulating YbIr 3 Si 7 .

Autor: Sato Y; Department of Physics, Kyoto University, Kyoto, 606-8502, Japan.; RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan., Suetsugu S; Department of Physics, Kyoto University, Kyoto, 606-8502, Japan., Tominaga T; Department of Physics, Kyoto University, Kyoto, 606-8502, Japan., Kasahara Y; Department of Physics, Kyoto University, Kyoto, 606-8502, Japan., Kasahara S; Department of Physics, Kyoto University, Kyoto, 606-8502, Japan.; Research Institute for Interdisciplinary Science, Okayama University, Okayama, 700-8530, Japan., Kobayashi T; Department of Physics, Kyoto University, Kyoto, 606-8502, Japan., Kitagawa S; Department of Physics, Kyoto University, Kyoto, 606-8502, Japan., Ishida K; Department of Physics, Kyoto University, Kyoto, 606-8502, Japan., Peters R; Department of Physics, Kyoto University, Kyoto, 606-8502, Japan., Shibauchi T; Department of Advanced Materials Science, University of Tokyo, Kashiwa, Chiba, 277-8561, Japan., Nevidomskyy AH; Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA., Qian L; Department of Chemistry, Rice University, Houston, TX, 77005, USA., Morosan E; Department of Physics and Astronomy, Rice University, Houston, TX, 77005, USA.; Department of Chemistry, Rice University, Houston, TX, 77005, USA., Matsuda Y; Department of Physics, Kyoto University, Kyoto, 606-8502, Japan. matsuda@scphys.kyoto-u.ac.jp.
Jazyk: angličtina
Zdroj: Nature communications [Nat Commun] 2022 Jan 19; Vol. 13 (1), pp. 394. Date of Electronic Publication: 2022 Jan 19.
DOI: 10.1038/s41467-021-27541-9
Abstrakt: Kondo lattice materials, where localized magnetic moments couple to itinerant electrons, provide a very rich backdrop for strong electron correlations. They are known to realize many exotic phenomena, with a dramatic example being recent observations of quantum oscillations and metallic thermal conduction in insulators, implying the emergence of enigmatic charge-neutral fermions. Here, we show that thermal conductivity and specific heat measurements in insulating YbIr 3 Si 7 reveal emergent neutral excitations, whose properties are sensitively changed by a field-driven transition between two antiferromagnetic phases. In the low-field phase, a significant violation of the Wiedemann-Franz law demonstrates that YbIr 3 Si 7 is a charge insulator but a thermal metal. In the high-field phase, thermal conductivity exhibits a sharp drop below 300 mK, indicating a transition from a thermal metal into an insulator/semimetal driven by the magnetic transition. These results suggest that spin degrees of freedom directly couple to the neutral fermions, whose emergent Fermi surface undergoes a field-driven instability at low temperatures.
(© 2022. The Author(s).)
Databáze: MEDLINE
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